1. Field of the Invention
The present invention is generally directed to the field of particulate material separating devices, and more particularly, to a computer controlled separator device for separating dry, granular, free-flowing material according to particle density.
2. Description of the Related Art
Conventional gravity separator devices use an inclined perforated separator deck, which is vibrated, in combination with an air flow directed vertically upwards through the separator deck in order to separate material into fractions or sections by weight. Typically, gravity separator devices are used to improve product quality in seed and grain, mineral, and recycling applications. The inlet end of the deck is elevated with respect to the outlet end to define an end raise. End raise is adjusted to control the rate at which material flows over the deck. A first side of the deck is elevated with respect to a second side to define a side tilt. Side tilt is adjusted to control the rate at which heavier material is conveyed up hill on the deck. By supplying vertically moving air, a lifting action is created that acts upon each particle in the bed of a product to be separated. The air flow also results in a vigorous washing effect whereby fine dust and dirt is removed from the product to be separated.
The separator deck is vibrated to provide an agitation and a conveying action. With each vibration stroke, the agitation action lifts the bed of material and throws it up into the air flow. In general, the air flow velocity is set at a value that is an average of that required to lift the bed of material. This value is lower than the terminal velocity of the particles so that, when lifted by the agitation action, all particles will fall back toward the deck surface against the air flow. The rate of fall is related to the weight of the particle and to the aerodynamic nature of the particle. Each individual particle varies from an average particle mass to some degree. In accordance with the degree of variance, heavier particles fall faster against the air flow and lighter particles fall slower against the air flow. When the bed of material has been subjected to a few lifting and falling cycles, stratified layers are generated, with the lightest material being on top of the bed and the most dense material collecting on the bottom of the bed. Intermediate particles having characteristics close to the average characteristics of the mass of the product are located in middle zones between the heaviest and lightest particles.
In addition to the agitation action, the vibration of the separator bed provides a conveying action. The conveying action imparts a thrust to the particles as they are lifted and thrown into the air. The deck surface retracts while the particles are in the air, and advances as the particles fall back to the deck surface. Heavier particles that are on the bottom of the bed are situated in closer contact with the deck surface, and are conveyed at a faster rate than lighter particles that are at the top of the bed. The deck surface is tilted in a direction opposite to the conveying action provided by the vibration. Lighter material that is on top of the bed is not affected as much by the conveying action, and tends to flow downhill in the direction of the side tilt.
With proper adjustment of air flow, separator bed vibration speed, and separator bed side tilt and end raise, a bed of material may be effectively separated. Denser particles on the bottom of the bed move uphill in one direction because of the vibrating conveying action. Lighter particles on the top of the bed flow downhill in an opposite direction because of the agitation action and side tilt. Intermediate particles move at a speed and in a direction that is directly related to the weight and aerodynamic qualities of the particles.
One technique for adjusting the end raise and side tilt in a gravity separator device is disclosed in U.S. Pat. No. 2,759,605 to Steele, wherein two screw jacks are used to accomplish these adjustments. A major disadvantage with this type of adjustment assembly is the need to release and secure clamps before and after adjustments are made. Another disadvantage is that the machine must be stopped in order to allow the operator to make any adjustments. This can be both time consuming and costly since any down-time takes away from productive separating time.
Another technique is shown in U.S. Pat. No. 5,024,334 to Misra et al., in which a detector detects the movement of control particles with respect to a gravity table in order to control a separation process. A disadvantage to this technique is that control particles must be added, thereby introducing unwanted impurities into the product to be separated.
In another device, shown in U.S. Pat. No. 4,563,271 to Schroder et al., a percussion jig has a carrier for material to be separated. In the discharge regulation system that supplies the separated materials to different outlets, a float generates a signal, which is used to control the discharge gate at the output.
U.S. Pat. No. 4,342,654 to Lambert discloses a separator having a liquid-filled tank with sensors to detect the level of separation of two layers in the bed of the separator. In response to the sensor signals, the system adjusts a solenoid valve to control the air venting process of the separator. U.S. Pat. No. 4,991,721 to Misra et al. shows sensing of the quantity of undersized material separated by a screen and of the quantity of oversized material separated by an air-lift to effect adjustments to the screen or air-lift.
Other prior art techniques, such as those described by U.S. Pat. No. 4,765,489 to Satake and U.S. Pat. No. 3,933,249 to Welsh et al., use light sensitive elements to monitor the product output from a product separator, and move a product recovering device in response to changes in product output.
It is an object of the present invention to provide a computer interface with a high-capacity separator device to improve efficiency and ease of operation.
It is a further object of the present invention to automate operator functions of a separator device in order to make more efficient use of production resources.
It is a further object of the present invention to provide a computer controlled separator device, in which the computer control system controls the functions of the separating device required for optimum performance.
It is yet another object of the present invention to provide a computer control system to monitor the operating parameters of a separating device and hold preset conditions indefinitely, automatically making adjustments to those parameters if changes in the operating environment, such as air pressure, temperature and humidity, so necessitate.
It is another object to provide a gravity separator control device that will store and record operating parameters for future use.
It is still another object of the present invention to provide a computer controlled separator device capable of monitoring the characteristics of the input material or output material, and which adjusts operating parameters accordingly to maintain a given standard of product quality.
It is a further object of the invention to provide a computer controlled separator device that will monitor final product quality and will adjust operating parameters to maintain reject product below certain levels and maintain acceptable product above certain levels.
It is another object to provide a computer controlled separator device that will monitor the final product to keep product that must be recycled to a minimum.
It is another object of the present invention to provide a computer controlled separator device that will monitor operating parameters an product quality and that will warn an operator when preset values are not maintained.
It is still a further object of the present invention to provide a computer controlled separator device that can be interfaced with other devices in a processing line of equipment.
The present invention is directed to a computer controlled separator device for separating heavier particulate material from lighter particulate material. The control system monitors the operation of the separator device and makes any adjustments necessary to maintain desired optimal operation.
According to the present invention, the operator may input values representing desired operating parameters and/or desired product characteristics of the separator device. Alternatively, these values may be programmed into the computer control system in accordance with optimal product or system standards. The computer control system monitors the operation of the separator device and makes any adjustments necessary to maintain operation in accordance with the selected or programmed values. Specifically, the computer control system may monitor incoming and outgoing product characteristics, i.e. particle weight, particle density, or particle size; and/or operating parameters, i.e. air flow, vibration speed, side tilt, end raise, feed rate divider knife position and cutout gate position. In response to monitoring signals, operating parameters of the separator device are adjusted. Thus, sensors provide product or operating information to the computer control system. The computer control system then processes the information, makes decisions based upon the current values of the information as compared to input or programmed values, and adjusts separator device operating parameters if necessary.